1. Field of the Invention
The present invention pertains to a processing system including screening and grinding devices for processing earth drilling cuttings and the like to form a slurry of fine particles and liquid which may be injected through wells into the earth as a way of disposal.
2. Background
The generation of wetted earth particles during drilling of oil and gas wells and the like, as well as the generation of certain types of grindable materials which may be disposed of through deep injection wells has resulted in the development of certain processes and systems for preparing slurries of finely ground particles which are suitable for deep well injection. U.S. Pat. No. 4,942,929, issued Jul. 24, 1990 to Malachosky et al, and U.S. Pat. Nos. 5,109,933 and 5,129,469, issued May 5, 1992 and Jul. 14, 1992, respectively, to J. E. Jackson, all assigned to the assignee of the present invention, describe disposal systems for earth drilling wastes and the like. In particular, the system described in the Jackson patent includes a modified centrifugal pump which is operable to reduce the particle size of certain types of earth material generated during the drilling of wells primarily by a shearing action. However, the drill cuttings disposal system described in the Jackson patent is not well suited to processing cuttings of relatively hard earth materials. In this regard, it has been determined that a device for reducing drill cuttings particle size, such as a ball mill or the like, is better adapted to handle certain sands, gravels and other earth materials that cannot be adequately ground by a shearing type action. A treatise entitled: "The Cuttings Grinder" by R. I. Smith, Society of Petroleum Engineers, Inc. (SPE 22092), 1991 , describes one system using a ball mill for grinding drill cuttings.
Still further, however, there has developed a need for a portable earth drilling cuttings processing system which is not only adapted to receive wet cuttings from drilling operations but also to receive and process cuttings which have been previously disposed of in so-called reserve pits associated with drilling operations. It is also desirable that a drilling cuttings processing system be provided which is adapted for operation in harsh environments and which may be easily moved from one site to another where drilling wastes are being generated or have previously been generated and disposed of on the earth's surface. Still further, there has been recognition of a need for a processing system that may be used to process materials similar to drill cuttings but which have been generated from other sources. It is to this end that the present invention has been developed.